Nephrology and experimental medicine in vivo, in vitro, and in silico

Abstract Experimental medicine has formed the basis for generating medical knowledge for several centuries. The development of various experimental tools introduced at different times in medical practice has allowed the acquisition of knowledge with increasingly sophisticated scientific bases. Consequently, through in vivo, in vitro and, more recently, in silico experiments, we have witnessed an uninterrupted collection of experimental data potentially valuable for medicine, especially for Nephrology. We are gradually contemplating the uniqueness of individuals for the benefit of life and human dignity.


Resumo
Experimental medicine has formed the basis for generating medical knowledge for several centuries.The development of various experimental tools introduced at different times in medical practice has allowed the acquisition of knowledge with increasingly sophisticated scientific bases.Consequently, through in vivo, in vitro and, more recently, in silico experiments, we have witnessed an uninterrupted collection of experimental data potentially valuable for medicine, especially for Nephrology.We are gradually contemplating the uniqueness of individuals for the benefit of life and human dignity.

IntRoductIon
Although nephrology is a relatively young specialty, created only in the mid-20th century, it combines many activities that routinely involve the replacement of kidney function.By repeatedly resuscitating the Internal Environment, nephrology promotes a medical service that can extend the lives of (physiologically anephric) patients by days, months, years or even decades.As a highly complex specialty, nephrology incorporates a series of medical knowledge that has been acquired over the course of medical history, contributing to physiological, pathophysiological, and therapeutic understanding.Nephrological knowledge has particularly benefited from experimental medicine, building basic and applied scientific concepts that permeate nephrological practice from simple urine analysis to xenotransplantation.

dIscussIon
The 19th century, the "Century of Sciences", was a period of systematization of thought and enthusiasm for discoveries.Until then, Western medical schools generated and transmitted descriptive knowledge supported by classical works (16th and 17th centuries) such as those of Andreas Vesalius 1 , the "father of modern anatomy" (Figure 1), and William Harvey 3 , the "father of physiology".The knowledge of medicine was only visible macroscopically and in vivo.The insight of experienced observers represented the most effective source teaching the art of healing.
Microscopy was created in the 16th century when Robert Hooke 4 described the cell.Marcello Malpighi 5 (17th century) was the first anatomist to use it to identify erythrocytes and capillaries.In his work "De Viscerum Structura" from 1666 on human descriptive anatomy, Malpighi dedicates a section entitled "De Renibus", in which he describes the structures of the kidney.In the 19th century, immersion techniques and binocular lenses contributed to histopathological studies and an in-depth knowledge of the cell nucleus.Medicine incorporated the visible in vitro, now on a microscopic scale.
In 1801, Philippe Pinel 6 , the "father of modern psychiatry", published the "Medical-philosophical Treatise on Mental Alienation", in which he differentiates behavioral deviations from mental illness.Medicine, which until then had been limited to the clinic and surgery, inaugurated a new specialty with "Alienism", which was humanistic and secular in its humanistic focus on the individual.Alienism brought patients together in hospitals to organize observation, classification, and treatment in vivo.
Also in the early 1800s, Richard Bright 7 began clinical studies and autopsies of patients with nephritis, characterizing "Bright's Disease".His pioneering work made him the "father of nephrology".
The stethoscope, created in 1819 by René Laennec 8 , established audible medicine, promoting semiological maneuvers and non-invasive in vivo experiments.Since the synthesis of urea (Friedrich Wöhler 9 -1828), modern biochemistry emerged.Friedrich Miescher 10 described nucleic acids, Louis Pasteur 11 rejected "spontaneous generation", and Claude Bernard 12 created the concepts of "Internal Environment" and gluconeogenesis.
While the theory of evolution (Charles Darwin-1859) 13 caused controversy in academic circles, Gregor Mendel 14 , the "father of genetics", investigated heredity, innovating with the use of mathematical foundation of intergenerational macroscopy, published in 1865.In the same year, Claude Bernard introduced the binomial observationexperimentation in his "Introduction to the Study of Experimental Medicine".Like Descartes, he aroused interest in the use of the scientific method, establishing a new path for medical-scientific thinking.Without knowing the intimacy of the cell and its molecular components, the "father of modern physiology" sought a hierarchical understanding in the biological symphony, heralding the dawn of renal physiology.
In the scientific boom of the 19th century, biological components, molecules, and chemical elements were gradually identified, supported by the periodic table recently created by Dmitri Mendeleev 15 (1869).Humanity was surprised to learn that the human body is not particular and is composed of the same matter found in other bodies in nature.During this period, there was a resurgence of rationalism, edited by Hippocrates (460 BC-377 BC), a thought that had lain dormant for centuries by theological currents applied to medicine.Biochemical processes and physical phenomena were gradually reproduced with the aid of test tubes.Medical thinking incorporated microscopy (microscopically visible medicine) and biochemistry (invisible medicine), inaugurating the promising era of cell biology.experimental medicine contributions to modern nephrology Willian Osler 16 combined clinic and pathology, identified platelets, and published "Principles and Practice of Medicine" (1892) being considered the "father of modern medicine."Science emanated from vivaria and new research tools, with emphasis on spectroscopy.In 1895, Wilhelm Roentgen 17 surprised the world with the first x-ray (of his wife's hand).He opened up a non-invasive way into the human body, inaugurating a new dimension of macroscopically "visible" medicine.The method found immediate application in the First World War.Non-invasive approaches have evolved in parallel with advances in physics.Ultrasonography and ultrasound, computed tomography, nuclear medicine, and nuclear magnetic resonance emerged.Visible medicine introduced functional imaging methods, enriching the tools of in vivo experimental medicine.At the same time, on a microscopic scale, Santiago Ramón y Cajal 18 inaugurated modern neuroscience by isolating brain nerve cells (Cajal cells) and was awarded the Nobel Prize in Physiology or Medicine (1906) alongside with Camillo Golgi.
Edward Jenner, the "father of immunology", observed the protection of humans from smallpox by the cowpox virus in 1796.Elie Metchnikoff 19 (1882) conceptualized immunology, inaugurating the term phagocytosis and shared the Nobel Prize in Medicine with Paul Ehrlich in 1908.
Once the cells were known, the challenge was to cultivate them in vitro.The feat achieved with cell cultures at the beginning of the 20th century, boosted clinical and experimental medicine, from cell physiology to the development of organ and tissue transplants.Microscopically visible medicine was thus subjected to experimental conditions drawn from invisible medicine.
At the turn of the 20th century, Willem Einthoven 20 studied electrophysiology phenomena and was awarded the Nobel Prize in 1924 for the development of the electrocardiogram.Invisible aspects were graphically translated into electrophysiological information used clinically and experimentally in vivo.
During the Second World War, Willen Kolff 21 created the first blood bank in Europe in 1940, developed the prototype of an artificial kidney, and performed the first successful hemodialysis in 1945.Later, in 1967, Kolff 22 also developed the artificial heart and is considered the "father of artificial organs".
In the 1950s, Peter Brian Medawar 23 developed the theory of Acquired Immune Tolerance, paving the way for the success of transplantation and received the Nobel Prize in Physiology or Medicine in 1960, being considered the "father of organ transplants".
The nucleic acids described in 1869 revealed the structure of DNA in 1953 by James Watson and Francis Crick 24 , the 1962 Nobel laureates.This marked the birth of molecular biology, which deals with the phenomena of replication, transcription, and translation involving DNA, RNA, and proteins.Sequential strategies made the genome project feasible, which was completed in 2003, involving 5000 researchers.Molecular biology provides information about the past, present, and future.Molecular panels and gene therapies provide therapeutic alternatives for genetic diseases and precision oncology.Through molecular biology, invisible medicine was finally incorporated into clinical practice and experimental medicine.
After decades of trials and in vivo and in vitro experiments, John Merrill and Joseph Murray 25 performed the first successful kidney transplant between identical twins in 1954.The development of immunosuppressive drugs allowed the first successful transplant from a deceased donor by the same team in 1962.These achievements led to Murray being awarded the Nobel Prize in Medicine in 1990.
In the 21st century, translational medicine emerged, a rapid connection from the bench to the bedside that aims to translate primary in vitro knowledge directly into clinical application in vivo.
Since Archibald Pitcairne 26 , the "father of mathematical medicine" (17th century), the medical sciences no longer have to do without mathematics for biological axioms and the prediction of biological phenomena, automatically incorporating biostatistics and epidemiology.Mathematics is to 20th and 21st century medical knowledge what the microscope was to the 19th century, especially in omics approaches (genomics, proteomics and metabolomics).The stages of knowledge were accelerated by the analytical scale and data processing of information technology.The "hightech" tools herald the acquisition of innovative expertise, that flows visibly and invisibly into medical practice.In addition to numbers and letters, algorithms integrate biological models into artificial intelligence, bringing simulations and tests to the computer screen, sparing animals (in vivo), cells, or other biological elements (in vitro), inaugurating in silico experimental medicine.
Aided by information technology and the observation of the defense mechanisms of some bacteria that protect themselves from viruses, CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) was developed.This method made genome editing possible and represented a technological revolution by enabling the introduction of specific manipulations to modify the DNA of living cells, animals, or plants.Emmanuelle Charpentier and Jennifer Doudna 27 were awarded the 2020 Nobel Prize in Chemistry for this achievement.This technique changed the prognosis for a series of diseases caused by genetic disorders and allowed the therapeutic use of genetically modified cells and tissues.
Recently (March 2024), we have seen that the application of the CRISPR method in pig cells allowed the first xenotransplantation of a genetically modified pig kidney into a human patient, based on a series of previous experiments.This is a true milestone for clinical and experimental medicine.In this feat, the team led by Leonardo Riella 28 brought together a succession of multiple findings from experimental medicine in vivo, in vitro, and in silico.
In this 21st century, we are living in an auspicious new era, in which cybernetic tools are becoming increasingly important and triggering new waves of in silico testing.However, virtual medical reality must also be subordinated to the same elementary ethical principles of medicine and must never evade humanistic principles by preserving the ancient values that have governed the dignity of human life, in respect for the "medicine of the soul" since the beginning of time.

conclusIon
Modern medicine is evolving into precision medicine, focusing on prevention and the uniqueness of the individual rather than just the general characteristics of diseases.The various stages that medical knowledge has passed through in the course of history have not been without experimental medicine, whose modern tools make it possible to be practiced in vivo, in vitro, and in silico, for the benefit of life and human dignity.

conflIct of InteRest
The author declare that he has no conflict of interest related to the publication of this manuscript.

Figure 1 .
Figure 1.Drawing of the work of Vesalius (1543) that revolutionized knowledge and the teaching of anatomy in the 16th century 2 .